In the process of drilling a wellbore, frictional forces acting against the drill pipe or other component running through the wellbore limit the maximum length or depth to which the wellbore may be drilled. Conventional methods of drilling achieve lengths of 10,000 to 15,000 feet.
Prior art solutions include mechanisms for vibrating the drill pipe during drilling in order to convert static frictional forces on the drill pipe to dynamic frictional forces between the drill pipe and the wall of the wellbore. One method of vibrating drill pipe within a wellbore includes using a valve in the drill string to create a pressure pulse in conjunction with a shock sub. The pressure pulse causes the shock sub to stretch and the drill pipe to vibrate axially, which allows the drill pipe to reach greater lengths or depths within the wellbore. Certain prior art pressure pulse generation tools use a separate power section to activate the valve. These tools, however, use elastomers that are sensitive to heat and chemicals in drilling mud. Other prior art tools use poppet valves that move up and down to open and close fluid ports. These poppet valve tools, however, are very complicated and cannot be used with drilling mud containing any kind of solids. Furthermore, conventional vibrating tools and methods provide vibration during the entire duration of drilling, i.e., from beginning of pumping drilling fluid through the drill pipe and vibration tool. The constant vibration places undue wears on the vibration tool resulting in reduce longevity.